drm/ttm: fix pipelined gutting v2

We need to make sure to allocate the sys_mem resource before the point
of no return.

v2: add missing return value checking, also handle idle case
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210608081931.11339-1-christian.koenig@amd.com

drivers/gpu/drm/ttm/ttm_bo_util.c

@@ -582,9 +582,14 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
 {
 	static const struct ttm_place sys_mem = { .mem_type = TTM_PL_SYSTEM };
 	struct ttm_buffer_object *ghost;
+	struct ttm_resource *sys_res;
 	struct ttm_tt *ttm;
 	int ret;
 
+	ret = ttm_resource_alloc(bo, &sys_mem, &sys_res);
+	if (ret)
+		return ret;
+
 	/* If already idle, no need for ghost object dance. */
 	ret = ttm_bo_wait(bo, false, true);
 	if (ret != -EBUSY) {
@@ -592,14 +597,15 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
 			/* See comment below about clearing. */
 			ret = ttm_tt_create(bo, true);
 			if (ret)
-				return ret;
+				goto error_free_sys_mem;
 		} else {
 			ttm_tt_unpopulate(bo->bdev, bo->ttm);
 			if (bo->type == ttm_bo_type_device)
 				ttm_tt_mark_for_clear(bo->ttm);
 		}
 		ttm_resource_free(bo, &bo->resource);
-		return ttm_resource_alloc(bo, &sys_mem, &bo->resource);
+		ttm_bo_assign_mem(bo, sys_res);
+		return 0;
 	}
 
 	/*
@@ -615,13 +621,11 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
 	ret = ttm_tt_create(bo, true);
 	swap(bo->ttm, ttm);
 	if (ret)
-		return ret;
+		goto error_free_sys_mem;
 
 	ret = ttm_buffer_object_transfer(bo, &ghost);
-	if (ret) {
-		ttm_tt_destroy(bo->bdev, ttm);
-		return ret;
-	}
+	if (ret)
+		goto error_destroy_tt;
 
 	ret = dma_resv_copy_fences(&ghost->base._resv, bo->base.resv);
 	/* Last resort, wait for the BO to be idle when we are OOM */
@@ -631,6 +635,14 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
 	dma_resv_unlock(&ghost->base._resv);
 	ttm_bo_put(ghost);
 	bo->ttm = ttm;
+	bo->resource = NULL;
+	ttm_bo_assign_mem(bo, sys_res);
+	return 0;
 
-	return ttm_resource_alloc(bo, &sys_mem, &bo->resource);
+error_destroy_tt:
+	ttm_tt_destroy(bo->bdev, ttm);
+
+error_free_sys_mem:
+	ttm_resource_free(bo, &sys_res);
+	return ret;
 }